Highly Efficient Fabrication of Polymer Nanofiber Assembly by Centrifugal Jet Spinning: Process and Characterization

Abstract

Centrifugal jet spinning (CJS) is a highly efficient, low-cost, and versatile method for fabricating polymer nanofiber assemblies, especially in comparison to electrospinning. The process uses centrifugal forces coupled with the viscoelastic properties and the mass transfer characteristics of spinning solutions to promote the controlled thinning of a polymer solution filament into nanofibers. In this study, three different spinning stages (jet initiation, jet extension, and fiber formation) were analyzed in terms of the roles of fluid viscoelasticity, centrifugal forces, and solvent mass transfer. Four different polymer solution systems were used, which enables a wide range of fluid viscoelasticity properties and solvent mass transfer properties, and polymer fibers were fabricated under different rotational speeds for these polymer solutions. The key dimensionless groups that determine the product morphology (beads, beads-on-fiber, and continuous fiber) and the radius of the fiber (when fibers are formed) were identified. The obtained morphology state diagram and fiber radius model were tested using a fifth polymer solution system. Results indicate that Weissenberg number and capillary number are important during the fiber extension stage to enable fiber formation while the elastic processability number is the determinative dimensionless number for fiber diameter prediction.

Development of Molecular Anisotropy in Centrifugally Spun Fibers as Compared to Electrospun Fibers

“…This maybe the result of insufficient speeds used in the spinning process resulting in the fibers being wound up as they are produced. In several reports an airfoil has been used which may aid in airflow and deposition of the fibers further away from the spinneret …”

“…This chaotic whipping means that the jet velocity is significantly higher than the 4.2 ms −1 measured over the needle tip to collector distance, perhaps making the speed more comparable to that of the higher speeds in the centrifugal spinning system, but without the jet breakage. Several reports have mentioned the use of an airfoil incorporated into their equipment design for centrifugal spinning . This maybe something to consider that may aid in fiber stretching and solvent evaporation, thereby impacting on the observed level of molecular anisotropy developed in the fibers.…”

Manipulating characteristic timescales and fiber morphology in simultaneous centrifugal spinning and photopolymerization

“…[54]. These interesting similarities of fiber morphology development as a function of De and Wi suggest that, despite the drastic differences in mechanisms of fluid jet solidification, the underlying fiber drawing forces and fiber trajectory, the elastic forces and conditions required to form stable fluid jet and uniform fibers in this reactive fiber spinning method are comparable to that of a non-reactive fiber spinning method, provided sufficiently rapid curing kinetics.…”

“…, where U is the spin speed and a is the distance between the orifice and the spinning axis [54]. [54].…”

Controlling the Aspect Ratio of Supramolecular Fibers by Ultrasonication

“…These properties render polymer nanofibers as interesting candidates to be used as material in, for example, air and water filtration and biomedical applications including tissue engineering and drug delivery as well as composite reinforcement, polymer melt modifiers, and polymer foam nucleation agents . Typically, polymer micro and nanofibers with defined fiber diameters are fabricated by top‐down processes from melt or solution through nozzles such as melt blowing, centrifugal spinning, and electrospinning . In these continuous processes, filaments with infinite fiber lengths are obtained.…”